Solid wall insulation possibility?

[electricianid]

What about insulating solid wall buildings by plastering with a mix of lime sand and LECA or similar, in the same way as limecrete floors are built?
It insulates well enough for UFH and it is obviously breathable. Or alternativley what about a stud wall with lath + limplaster on the room side, a breathable membrane (hessian?) on the void side and filled between with LECA?

 

[andrew gayton]

or use one of the readily available vapour permeable rigid insulation products!

 

[electricianid]

Sounds interesting Andrew, do you know any websites/tradenames of the new products?

 

[BMcD]

Never used this but saw it on Lime-Green's website

http://www.lime-green.co.uk/images/Product/HEMP_PLASTER.pdf

http://www.lime-green.co.uk/products/index.php?Sec=1&Lt1=&Ct2=2&Clv=3

 

[worms]

readily available

Perhaps true in the South!

 

[electricianid]

Wow, the hemp/lime insulating plaster is such a great idea, no stud wall, no vapour check, no space age insulation, I am completley sold on it.
I am still none the wiser on the "vapour permeable rigid insulation products!" mentioned by Andrew though, I would really like to investigate these, I would be grateful if some kind soul could point me in the right direction?

 

[andrew gayton]

diffutherm for one.........................

 

[Mark]

the problem is that you need a significant thickness of the hemp stuff to have a decent effect - how much room can you loose?

I would recommend the aecb web site for this sort of thing.

 

[electricianid]

An account of one persons experience of diffutherm involved "clay plaster to level the wall, 100mm thick Diffutherm boards fixed with insulated fischer fixings, clay or lime plaster undercoat and finishing coat"
Sounds like a bit of a carry on to me, but then this method (100mm of diffutherm) ought to achieve a similar U value to celotex, whereas I'm sure that a hemp/lime plaster would not insulate to that degree. Having said that the hemp/lime can only be applied to a max depth of 80mm which would intrude into the room the least compared to diffutherm and celotex/stud. Will look at AECB later.

 

[andrew gayton]

an undulating wall will take diffutherm quite well. some dubbing out of 'holes' may well be required..................... but not the provision of a levelled surface.... the material is quite flexible - within reason - and will take lime plaster (no i do not have shares by the way)

 

[MrT]

Another possibiliy is cork which will perform in a similar way to diffutherm. It is not suppiled with tounge and groove though so you will need to think about the board edges.

 

[electricianid]

As I understood it the diffutherm board is to be pressed into the clay plaster coat whilst it is still wet, presumably to ensure a continuous moisture path but it would sure help to not have to use the clay layer at all.
I also read on a website that it was not possible to use lime on diffutherm, can't remember which one (I have looked at dozens today) but I can't imagine why not if its basically wood pulp. Its certainly good stuff though, high sound and thermal insulation, increase of thermal mass, perhaps a little pricey at least for the 100mm option, but the thing that concerns me is what would happen if you tried to chase out cable runs? Obviously it would be best to get them all in prior to insulation but you might want to make alterations in the future. Do you have experience of diffutherm Andrew, or anyone else for that matter?

 

[andrew gayton]

I would have thought that it could be cut out with an angle grinder with a diamond disc.............